Effects of excessive iodine intake during the perinatal period on thyroid function and higher brain functions in...

Iodine is an essential trace element crucial for thyroid hormone synthesis. While iodine deficiency has been recognized as a global health concern due to its association with hypothyroidism, certain regions may face challenges related to excessive iodine intake. The impact of excessive iodine intake during the perinatal period on higher brain functions remains unclear. To address this gap, we conducted a study using an animal model to elucidate the effects of perinatal iodine excess on higher brain functions. Dams received specific drinking water (control, ×20 iodine (KIO₃ 37.4 mg/L), ×200 iodine (KIO₃ 374 mg/L)) from prior to mating until weaning. Pups received the corresponding drinking water until the end of the experiment. Behavior test battery was utilized to investigate the behavioral outcomes associated with perinatal iodine excess. Excessive iodine intake increased learning acquisition in females whereas it decreased exploration of social novelty in males. Conversely, mRNA levels of several genes related to learning and memory in the hippocampus were rarely affected. Overall, the present study highlights the consequences of excessive iodine intake during developmental periods. However, these effects were mild and varied by sex, warranting the further investigation.